A light emitting diode (LED) has a low working voltage, low power loss, high light emitting efficiency, short response time, pure light color, solid structure, high impact resistance, high vibration endurance, stable performance, light weight, small volume and low cost. The promotion of the technology has helped to increase the brightness of the LED, and LEDs are being used in increasingly diverse applications such as large-scale display screens, status indication, symbol lighting, signal displays, backlight of a liquid crystal display (LCD) and lighting in car.
Conventional LEDs may be bonded on a metal substrate for circuit connection. When bonding the LED, the LED leads may be welded to the metal substrate. However, the temperature of the LED is too high during welding, and the LED chip may be burned out. Further, when the LED is welded to the metal substrate, it is difficult that the LED positions to the metal substrate. Therefore, there are problems when the LED is welded on the metal substrate.